1. Field of the Invention
The present invention relates to a volume reducing agent for expanded polystyrene (EPS), methods and apparatus for processing EPS using a volume reducing agent to reduce the volume of EPS known as bulky waste, as well as to recycle used EPS and recover high quality polystyrene.
2. Description of the Related Art
EPS, also known as foamed styrene, has excellent thermal-protective or insulating properties and buffering effects. EPS is used throughout the world for a variety of different purposes including, for example, but not limited to transport packaging boxes for sea foods and shock-absorbing packing materials contained in package for home appliances.
EPS product is generally bulky, potentially causing disposal problems. For example, burning disposal of EPS can interfere with operation of a combustion furnace, and also has the problem of producing harmful gases. An additional problem of EPS having bulky property (or voluminous nature) is that there is a high vehicular transportation cost. Because EPS is normally soluble in some organic compounds such as aromatic hydrocarbons, hydrocarbon halides, etc., a particular disposal plant may be designed which enables waste EPS to be dissolved. However, such a plant must be run on a large scale and there are known potential environmental problems deriving from the resulting liquid product.
Another potential disposal process uses limonene, which can dissolve EPS completely. However, limonene has very low ignition point of 48xc2x0 C. and a strong odor, volatility and high consumption of limonene per EPS to be dissolved, all of which are undesirable properties. As a result, limonene is considered an undesirable compound to be used within disposal plant with respect to safety and environmental concerns.
Due to restricted rules regarding a clean environment in recent years, a recycling process for used EPS or methods of increasing recycling capability have considered a most urgent necessity. In response to this need, the inventors have developed a safe and effective recycling process of EPS as a result of intensive studies to solve the aforementioned problems based on the concept of reducing the volume of EPS, rather than dissolution.
Accordingly, an object of the present invention is to provide a safe and effective method for volume reducing of EPS and to raise recycling capability thereof.
According to one aspect of the present invention, there is provided a volume reducing agent for processing EPS, containing a first plasticizer having a solubility parameter less than the solubility parameter of the polystyrene; and a second plasticizer having a solubility parameter higher than the solubility parameter of the polystyrene, wherein the agent is in a liquid state, has the solubility parameter in the mixed state close to that of polystyrene to be processed, and transfers the resulting materials having reduced volume into gel-type products to be floated and easily separated.
According to another aspect of the present invention, there is provided a method for processing EPS including the steps of: preparing a volume reducing agent, the volume reducing agent containing a first plasticizer having a solubility parameter less than the solubility parameter of the polystyrene, and a second plasticizer having a solubility parameter higher than the solubility parameter of the polystyrene, wherein the agent in the mixed state is in a liquid state, has the solubility parameter close to that of polystyrene to be processed and transfers the resulting materials having reduced volume into gel-type products to be floated and easily separated; dipping in the volume reducing agent EPS that may be crushed and be in a status having a specific shape or nonspecific shape to thereby reduce the volume of the EPS; and dipping the volume-reduced EPS in a neutralization solution to thereby obtain recycled EPS material.
According to still another aspect of the present invention, there is provided an apparatus for processing EPS by using a volume reducing agent. The apparatus includes: a main vessel in which the volume reducing agent is under-filled and pre-crushed EPS in shape or shapeless states that are permeated into the volume reducing agent; and an entrapping device for soaking the EPS into the volume reducing agent and entrapping the EPS in a gel type floating state.
It is to be understood that both the foregoing general description and following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.